A comb-domain coded frequency modulated continuous wave lidar device and measurement method

Abstract

The application discloses a kind of comb domain coding frequency modulated continuous wave laser radar device and measuring method, belong to optoelectronic information technology field.The device includes optical frequency comb, optical beam splitter, measurement branch, local branch, transmitting optical system, optical combiner, dense wavelength division multiplexer, photodetector array and data processing system, the optical frequency comb is connected with the optical beam splitter, the optical beam splitter is connected with the measurement branch and local branch, the local branch is connected with transmitting optical system through optical circulator, transmitting optical system and the local branch are connected with dense wavelength division multiplexer through optical combiner, the dense wavelength division multiplexer is connected with the photodetector array, and the photodetector array is connected with the data processing system.The application is by comb domain coding and coherent merging technology, effectively suppresses mutual interference when working in multiple channels same frequency, improves system concurrent ability and the stability and anti-interference of ranging and speed measurement.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic information technology, specifically to a comb-domain encoded frequency-modulated continuous wave lidar device and measurement method. Background Technology

[0002] Frequency-modulated continuous-wave lidar (FM-WW) obtains its beat frequency by emitting linearly swept continuous light and coherently mixing it with a local oscillator. Distance measurement is achieved using the relationship between the beat frequency and the sweep frequency slope. Furthermore, it can combine the distance separated by upper and lower sweep frequencies with Doppler velocity, and has been widely applied in autonomous driving, robotics, and industrial measurement scenarios. Currently, in environments with multiple FM-WW lidars coexisting indoors, strong industrial reflection / scattering interference, and multi-machine collaborative ranging, if the center frequencies and sweep frequency parameters of multiple transmitters are close, significant mutual interference and cross-beat frequencies can easily occur at the receiver, leading to phenomena such as "false peaks, distance ghosting, and missed detections / false detections." Existing technologies typically employ time-division / frequency-division / space-division isolation methods, but these often require additional coordination, consume bandwidth, or increase hardware complexity, and have limited suppression of co-frequency asynchronous interference.

[0003] To address the aforementioned issues, there is an urgent need for a comb-domain encoded frequency-modulated continuous wave lidar device and measurement method to solve the problems associated with traditional methods. Summary of the Invention

[0004] The purpose of this invention is to provide a comb-domain encoded frequency-modulated continuous wave lidar device and measurement method. Each tooth of the optical frequency comb is used as a "natural subcarrier". Frequency-modulated continuous wave sweep is carried on each tooth to form multi-transmitter transmission. Distinguishing codes are applied to the comb teeth in the "comb domain". Matched filtering / correlation despreading corresponding to the codes is performed at the receiving end. This enables multiplexing and separation of different transmitters or different channels within the same optical bandwidth, and suppresses mutual interference by utilizing coding correlation.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A comb-domain encoded frequency-modulated continuous-wave lidar device includes: an optical frequency comb, an optical beam splitter, a measurement branch, a local oscillator branch, a transmitting optical system, an optical beam combiner, a dense wavelength division multiplexer, a photodetector array, and a data processing system. The optical frequency comb is connected to the optical beam splitter, the optical beam splitter is connected to the measurement branch and the local oscillator branch, the local oscillator branch is connected to the transmitting optical system via an optical circulator, the transmitting optical system and the local oscillator branch are connected to the dense wavelength division multiplexer via the optical beam combiner, the dense wavelength division multiplexer is connected to the photodetector array, and the photodetector array is connected to the data processing system.

[0007] The measurement branch includes a programmable optical filter, a first polarization controller, and a first I / Q optical modulator. The optical beam splitter is connected to the programmable optical filter, the programmable optical filter is connected to the first polarization controller, the first polarization controller is connected to the first I / Q optical modulator, the first I / Q optical modulator is connected to the optical circulator, and the first I / Q optical modulator outputs a frequency-modulated continuous wave measurement optical comb signal.

[0008] The local oscillator branch includes a second polarization controller and a second I / Q optical modulator. The optical beam splitter is connected to the second polarization controller, the second polarization controller is connected to the second I / Q optical modulator, the second I / Q optical modulator is connected to the optical beam combiner, and the second I / Q optical modulator outputs a frequency-modulated continuous local oscillator optical comb signal.

[0009] The transmitting optical system includes a collimator and a transmission grating. The optical circulator connects the collimator and the optical beam combiner. The collimator is connected to the transmission grating. The frequency-modulated continuous wave measurement optical comb signal is transmitted to the space scene to be measured through the optical circulator, collimator and transmission grating, and the echo is received. The echo is output to the optical beam combiner through the optical circulator.

[0010] The device also includes an arbitrary waveform generator, a first electrical beam splitter, a second electrical beam splitter, a bias controller, and a third point beam splitter. The arbitrary waveform generator is connected to the first I / Q optical modulator and the second I / Q optical modulator respectively through the first and second electrical beam splitters for driving and controlling them. The bias controller is connected to the first I / Q optical modulator and the second I / Q optical modulator through the third electrical beam splitter for providing DC bias and setting the operating point.

[0011] Furthermore, the first electrical beam splitter is connected to the RF1 terminal of the first I / Q optical modulator and the second I / Q optical modulator, the second electrical beam splitter is connected to the RF2 terminal of the first I / Q optical modulator and the second I / Q optical modulator, and the third electrical beam splitter is connected to the DC terminal of the first I / Q optical modulator and the second I / Q optical modulator.

[0012] Furthermore, the optical frequency comb is a mode-locked laser, a microcavity optical comb, or an electro-optic modulation optical comb.

[0013] Furthermore, the optical circulator is provided with a first port, a second port and a third port. The first port of the optical circulator is connected to the first I / Q optical modulator, the second port is connected to the collimator and the third port is connected to the optical beam combiner.

[0014] The present invention also provides a measurement method for a comb-domain encoded frequency-modulated continuous wave lidar device, applied to the aforementioned comb-domain encoded frequency-modulated continuous wave lidar device, comprising:

[0015] Step 1: Construct a comb-domain encoded frequency-modulated continuous wave lidar device, activate the optical frequency comb, and generate a frequency-modulated continuous wave lidar device containing... K The optical frequency of the comb teeth;

[0016] Step 2: Use an arbitrary waveform generator to set the modulation parameters of the linear frequency modulation signal, and configure the frame sequence in the arbitrary waveform generator so that different frames output different sweep directions of drive;

[0017] Step 3: Encode the optical comb domain using a programmable optical filter to generate an active comb tooth subset and generate a complex weighted code for each active comb tooth;

[0018] Step 4: Input the encoded optical comb into the first I / Q optical modulator and generate the measurement optical comb by continuous linear frequency modulation in a single-sideband manner, and emit it through the transmitting optical system; at the same time, the second I / Q optical modulator generates a local oscillator optical comb with the same slope as the measurement optical comb;

[0019] Step 5: Receive the echo, combine it with the local oscillator optical comb, and input it into a dense wavelength division multiplexer for wavelength division. Perform mixing and photoelectric detection on each comb branch to obtain the beat frequency electrical signal of the corresponding comb.

[0020] Step 6: Sample the beat frequency electrical signal and perform a fast Fourier transform within each frame to obtain discrete beat frequency observations;

[0021] Step 7: Perform matched filtering, despreading, and merging on the discrete beat frequency observations based on comb domain coding to obtain the beat spectrum of the target channel after removing interference;

[0022] Step 8: Based on the beat spectrum after removing interference from the target channel, perform peak detection on the beat spectrum in adjacent upper and lower sweep frequencies, extract the upper and lower sweep frequency beat frequencies corresponding to the same target, and solve for the distance and velocity of the target.

[0023] Further, in step 1, the first is defined. The optical frequency of the comb teeth is:

[0024] ;

[0025] In the formula, The starting frequency; The spacing between the comb teeth; K This refers to the number of comb teeth.

[0026] Further, in step 3, the optical comb is encoded using a programmable optical filter to generate an active comb tooth subset, specifically as follows:

[0027] In containing KIn the optical frequency comb signal of a comb tooth, a portion of the comb teeth are selected to participate in transmission and modulation, while the remaining comb teeth are turned off or strongly attenuated in the frame. Each comb tooth corresponds to a transmitter or channel. The transmitter, in the... The frame determines the activation subset as follows:

[0028] ;

[0029] Generate comb domain encoding complex weights for each activated comb tooth, as follows:

[0030] ;

[0031] In the formula, This is the amplitude code, used for amplitude weighting or on / off key control. =0 indicates that the comb tooth is not active in this frame; This is a phase code used for the design of separability between different channels; For the first The transmitter was in the... Frame applied to the first The coding of the comb teeth;

[0032] For different transmitters or channels When generating comb field encoding, make any The low cross-correlation constraint is satisfied on its active comb intersection as follows:

[0033] ;

[0034] In the formula, For the first The transmitter was in the... Frame applied to the first The coding of the comb teeth, ( ) * Indicates conjugate. It is limited to not exceeding a preset threshold; For the first The transmitter was in the... The activation subset of the frame;

[0035] The optical comb is input into a programmable optical filter, and complex amplitude equalization is applied to each comb tooth. A k Comb field encoding The inactive comb teeth are then subjected to strong attenuation to obtain the encoded optical comb output.

[0036] Further, in step 8, based on the beat spectrum after removing interference from the target channel, peak detection is performed on the beat spectrum in adjacent upper and lower sweep frequencies. The upper and lower sweep beat frequencies corresponding to the same target are extracted to solve for the distance and velocity of the target being measured. Specifically:

[0037] Based on the beat spectrum after interference removal from the target channel, peak detection is performed on the beat spectrum in adjacent up-sweep and down-sweep frequencies to extract the up-sweep beat frequency corresponding to the same target. With downscan frequency and beat frequency The solution is obtained for the target being measured. The distance and speed are:

[0038] ;

[0039] In the formula, The distance to the target object in the target channel. The measured velocity of the target channel. At the speed of light, This is the operating wavelength.

[0040] In summary, the present invention has at least one of the following beneficial technical effects:

[0041] 1. This invention introduces programmable comb domain coding and comb tooth subset activation in the comb tooth dimension of the optical frequency comb, and performs matching decoding and merging on the desired transmitter signal at the receiving end, so that the desired signal is enhanced and the undesired signal is suppressed, thereby effectively reducing mutual interference in the scenario where multiple transmitters work at the same frequency.

[0042] 2. This invention separates the echoes according to the comb teeth to obtain multiple beat frequency observations, and performs coherent merging in the comb tooth dimension to achieve the processing gain of "multi-comb tooth accumulation"; without relying on a significant increase in single-channel hardware bandwidth, it improves the effective signal-to-noise ratio and peak detection reliability of the measurement link.

[0043] 3. While retaining the parallel measurement capability of the optical comb, this invention introduces a comb domain encoding and receiver decoding merging mechanism, enabling multiple transmitters or multiple channels to achieve effective differentiation and mutual interference suppression under the same optical comb resources and frequency conditions. This reduces the dependence on "strict isolation / exclusive allocation of comb teeth" and improves the system's concurrent operation capability and the stability of ranging and velocity measurement results in complex scenarios. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0045] Figure 2 This is a schematic diagram of the method flow of the present invention;

[0046] Figure 3A schematic diagram of an embodiment of the optical frequency comb spectrum and comb tooth subset activation provided by the present invention;

[0047] Figure 4 This is a schematic diagram illustrating the baseline beat spectrum suppression effect of a traditional single-comb tooth.

[0048] Figure 5 This is a schematic diagram illustrating the beat spectrum suppression effect after comb-domain coding and despreading merging in this invention;

[0049] Figure 6 This is a schematic diagram illustrating the processing gain effect of comb-domain encoding, despreading, and merging provided by the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0051] like Figure 1 As shown, the present invention provides a comb-domain encoded frequency-modulated continuous-wave lidar device, comprising: an optical frequency comb, an optical beam splitter, a measurement branch, a local oscillator branch, a transmitting optical system, an optical beam combiner, a dense wavelength division multiplexer, a photodetector array, and a data processing system. The optical frequency comb is connected to the optical beam splitter, the optical beam splitter is connected to the measurement branch and the local oscillator branch, the local oscillator branch is connected to the transmitting optical system via an optical circulator, the transmitting optical system and the local oscillator branch are connected to the dense wavelength division multiplexer via the optical beam combiner, the dense wavelength division multiplexer is connected to the photodetector array, and the photodetector array is connected to the data processing system.

[0052] The measurement branch includes a programmable optical filter, a first polarization controller, and a first I / Q optical modulator. The optical beam splitter is connected to the programmable optical filter, the programmable optical filter is connected to the first polarization controller, the first polarization controller is connected to the first I / Q optical modulator, the first I / Q optical modulator is connected to the optical circulator, and the first I / Q optical modulator outputs a frequency-modulated continuous wave measurement optical comb signal.

[0053] The local oscillator branch includes a second polarization controller and a second I / Q optical modulator. The optical beam splitter is connected to the second polarization controller, the second polarization controller is connected to the second I / Q optical modulator, the second I / Q optical modulator is connected to the optical beam combiner, and the second I / Q optical modulator outputs a frequency-modulated continuous local oscillator optical comb signal.

[0054] The transmitting optical system includes a collimator and a transmission grating. The optical circulator connects the collimator and the optical beam combiner. The collimator is connected to the transmission grating. The frequency-modulated continuous wave measurement optical comb signal is transmitted to the space scene to be measured through the optical circulator, collimator and transmission grating, and the echo is received. The echo is output to the optical beam combiner through the optical circulator.

[0055] The device also includes an arbitrary waveform generator, a first electrical beam splitter, a second electrical beam splitter, a bias controller, and a third point beam splitter. The arbitrary waveform generator is connected to the first I / Q optical modulator and the second I / Q optical modulator through the first and second electrical beam splitters, respectively, for driving and controlling them. The bias controller is connected to the first I / Q optical modulator and the second I / Q optical modulator through the third electrical beam splitter, for providing DC bias and setting the operating point.

[0056] The following describes the operation of the comb-domain encoded frequency-modulated continuous wave lidar device. The optical frequency comb emits an S-path light, which is split into S1 and S2 paths after passing through an optical beam splitter. The S1 path passes through a programmable optical filter, a first polarization controller, and a first I / Q optical modulator in sequence, and then outputs an S3 path light. The S2 path passes through a second polarization controller and a second I / Q optical modulator in sequence, and then outputs an S4 path light. The S4 path passes through an optical circulator, a collimator, and a transmission grating in sequence before being emitted onto the surface of the target. After reflection, it passes through a transmission grating, a collimator, and an optical circulator in sequence, and then outputs an R-path light. The S4 path light and the R path light pass through an optical beam combiner and are then input into a dense wavelength division multiplexer. After photoelectric detection by the photodetector array, they enter the data processing system together for target information processing.

[0057] The following is a detailed description of each component of the device:

[0058] The optical frequency comb is used for output. An optical frequency comb laser with equally spaced comb teeth; the optical frequency comb can be a mode-locked laser, a microcavity optical comb, an electro-optic modulated optical comb, etc.

[0059] The programmable optical filter is used to apply amplitude and phase weights to each tooth of the optical frequency comb to achieve power equalization and comb domain encoding.

[0060] The arbitrary waveform generator is used to generate two orthogonal continuous linear frequency modulated electrical signals, I and Q, to drive the first I / Q optical modulator and the second I / Q optical modulator; the I-channel electrical signal is divided into D-channels by the first electrical beam splitter. I1 D I2 Two electrical signals, D I1 The electrical signal is input to the RF1 radio frequency input port of the first I / Q optical modulator, D I2The Q-channel electrical signal is input to the RF1 radio frequency input port of the second I / Q optical modulator; the Q-channel electrical signal is then passed through the first electrical beam splitter to obtain the D signal. Q1 D Q2 Two electrical signals, D Q1 The electrical signal is input to the RF2 radio frequency input port of the first I / Q optical modulator, D Q2 The input is fed into the RF2 radio frequency input port of the second I / Q optical modulator;

[0061] The bias controller is used to generate two DC signals, C1 and C2, which are used to adjust and control the operating bias points of the first I / Q optical modulator and the second I / Q optical modulator, respectively. The DC signal C1 is input to the DC input port of the first I / Q optical modulator, and the DC signal C2 is input to the DC input port of the second I / Q optical modulator.

[0062] The first I / Q optical modulator is used to generate a comb-domain encoded frequency-modulated continuous wave optical comb signal S3, which is used as a measurement optical signal;

[0063] The second I / Q optical modulator is used to generate a frequency-modulated continuous wave optical comb signal S4 with the same sweep slope as the S3 optical comb signal, which is used as the local oscillator signal;

[0064] The optical circulator is provided with first, second, and third ports for cyclically transmitting light from the first port to the second port and from the second port to the third port. The first port of the optical circulator is connected to a first I / Q optical modulator, the second port is connected to a collimator, and the third port is connected to an optical combiner. After entering from the first port of the optical circulator and exiting from the second port, the output beam is collimated by the collimator and then enters a transmission grating to be projected onto the target surface. After being reflected by the target surface, the beam passes through the transmission grating and the collimator in sequence, enters from the second port of the optical circulator, and then exits from the third port as R-path light.

[0065] The collimator is used to collimate the light beam;

[0066] The transmission grating is used to spatially separate different frequencies (comb teeth) in the comb-domain encoded frequency-modulated continuous wave optical comb signal and project them into the space environment.

[0067] The dense wavelength division multiplexer is used to split the combined S4 and R beams into different output ports according to different comb teeth, and then send them into the photodetector array for coherent mixing to obtain the beat frequency electrical signal corresponding to each comb tooth.

[0068] The data processing system is used to process the beat frequency sequence to obtain distance and velocity information for different channels.

[0069] like Figure 2As shown, the present invention also provides a measurement method for a comb-domain encoded frequency-modulated continuous wave lidar device, applied to the aforementioned comb-domain encoded frequency-modulated continuous wave lidar device, comprising:

[0070] Step 1: Construct a comb-domain encoded frequency-modulated continuous wave lidar device, activate the optical frequency comb, and generate a frequency-modulated continuous wave lidar device containing... K The optical frequency comb signal of each comb tooth, wherein the first tooth... The optical frequency of the comb teeth is:

[0071] (1)

[0072] In the formula, The starting frequency; The spacing between the comb teeth; K This refers to the number of comb teeth;

[0073] Step 2: Use an arbitrary waveform generator to set the modulation parameters of the linear frequency modulation signal, and configure the frame sequence in the arbitrary waveform generator so that different frames output different sweep directions of drive, specifically:

[0074] The slope is The linear frequency modulation drive is configured as an up-sweep frame, with a slope of The linear frequency modulation drive is configured as a down-sweep frame, so that the up-sweep frame and the down-sweep frame alternate or appear in pairs in time, where the sweep slope is:

[0075] (2)

[0076] in, For linear frequency modulation slope, B This is the bandwidth for a single frame sweep. T The duration of a single-frame frequency sweep. This represents the scanned frame index, with each frame corresponding to a time interval of 1 / 2. ;

[0077] Step 3: Encode the optical comb domain using a programmable optical filter to generate an active comb tooth subset, specifically including the following steps:

[0078] Step 301: First, generate the active comb tooth subset, such as Figure 3 As shown, in the case of K In an optical frequency comb with a set of teeth, only a portion of the teeth are selected for transmission / modulation, while the remaining teeth are either "turned off" or strongly attenuated in that frame. Each tooth corresponds to a transmitter or channel, specifically for the first... The transmitter, in the... The frame determines the activation subset as follows:

[0079] (3)

[0080] For each activated comb tooth, generate a comb domain encoding complex weight, as follows:

[0081] (4)

[0082] In the formula, This is the amplitude code, used for amplitude weighting or on / off key control; when =0 indicates that the comb tooth is not active in this frame; This is a phase code used for the design of separability between different channels; For the first The transmitter was in the... Frame applied to the first The coding of the comb teeth;

[0083] For different transmitters or channels When generating comb field encoding, make any It satisfies a low cross-correlation constraint on the intersection of its activated comb teeth:

[0084] (5)

[0085] In the formula, For the first The transmitter was in the... Frame applied to the first The coding of the comb teeth, ( ) * Indicates conjugate. To be limited to not exceeding a preset threshold, For the first The transmitter was in the... The active subset of the frame is selected so that the non-target transmitter components are difficult to coherently superimpose in the despreading and merging process in step 7, thereby reducing the mutual winding of co-frequency coexistence.

[0086] Step 302: Input the input optical comb into the programmable optical filter and apply complex amplitude equalization to each comb tooth. A k Comb field encoding The inactive comb teeth are then subjected to strong attenuation to obtain the encoded optical comb output.

[0087] Step 4: Input the comb-domain encoded optical comb output from Step 2 into the first I / Q modulator, and configure the first I / Q modulator to a single-sideband modulation state to achieve continuous linear frequency modulation; switch the sweep direction frame by frame in the frame sequence so that the upper sweep frame and the lower sweep frame appear alternately or in pairs: apply a positive slope sweep drive to the first I / Q modulator in the upper sweep frame, and apply a negative slope sweep drive to the first I / Q modulator in the lower sweep frame, thereby generating up-sweep and down-sweep frequency-modulated light in different frames respectively; then transmit it to the space scene through the transmitting optical system (optical circulator, collimator and transmission grating for transmission to the space scene). This invention uses the first... Taking a frame as an example, let the time within the frame be... Then the first The light field of each transmitter in this frame can be represented as:

[0088] (1) When the first When the frame is an up-sweep frame, we have:

[0089] (6)

[0090] (2) When the first When the frame is a down-sweep frame, we have:

[0091] (7)

[0092] In the formula, For time variables, A k For the first To ensure stable beat frequency in coherent reception, the local oscillator and the transmitted light preferentially use the same modulator as the first I / Q modulator within the same frame, and both are single-sideband modulated by the same electrically driven synchronously controlled I / Q modulator. This ensures that the local oscillator and the transmitted light have the same sweep direction and slope amplitude within that frame. .

[0093] Step 5: Receive the echo signal from the space scene, combine it with the local oscillator signal, and input it into a dense wavelength division multiplexer for wavelength division multiplexing, so that the first... The echo corresponding to the comb teeth and the first The local oscillator branches corresponding to each comb tooth output their respective values; subsequently, mixing and photoelectric detection are performed on each comb tooth branch to obtain the corresponding... The beat frequency electrical signal of the comb teeth. Among them, the local oscillator light is in the first... The frame and the emitted light have the same sweep direction and slope amplitude. This ensures that the beat frequency falls within the sampleable bandwidth.

[0094] Step 6: Sample the beat frequency electrical signal output from each comb branch in Step 5, and sample it in each frame. Perform a Fast Fourier Transform within the inner quadrant to obtain the first... The comb teeth are in the first Discrete beat frequency observations of frames .in, For comb tooth index, This refers to the frequency bin index of the output after the Fast Fourier Transform. For frequency sweep index frames;

[0095] Step 7: Perform matched filtering despreading on the target transmitter to separate the target channel and suppress mutual interference. This process is equivalent to using the target code as weights to align the target components on each comb tooth and coherently superimpose them for enhancement, while non-target components are suppressed by incoherent superposition due to coding mismatch and difficulty in alignment. (For the target transmitter...) Using the comb domain encoding determined in step three Observations on each comb tooth After performing matched filtering, despreading, and merging, we obtain:

[0096] (8)

[0097] In the formula, For the target launch channel in the first The comb tooth subset of frame activation, ( ) * Indicates conjugate. For the first The comb teeth are in the first Frame, beat spectrum Complex value observations for each bin. For despreading and merging output, i.e., the target channel The pulse spectrum after interference removal.

[0098] Step 8: Despreading and merging output based on the result obtained in Step 7 In adjacent up-scan and down-scan frequencies respectively, Follow Peak detection is performed on the spectral distribution to extract the up-scan beat frequencies corresponding to the same target. With downscan frequency and beat frequency (Preferably use pairing of two adjacent frames to delay the target) With Doppler frequency (Approximately unchanged during pairing). The target channel is thus obtained. The distance and velocity of the target being measured are:

[0099] (9)

[0100] In the formula, The distance to the target object in the target channel. The measured velocity of the target channel. At the speed of light, This is the operating wavelength.

[0101] like Figure 4 and Figure 5 The figure shows the effect of the target and interference channels in the comb domain coding and despreading merging process in step 7 of the method of the present invention. Figure 4 The image shows the spectrum of a traditional single-comb baseline frame, including the target peak and interference peaks, reflecting the spectral distribution under traditional single-channel observation. In the figure, the target peak and interference peak are located adjacent to each other in the up-scan frame, making them difficult to distinguish effectively. Figure 5 The image shows the beat spectrum after using the comb-domain coding and despreading merging method of this invention. The target peak is significantly enhanced, while the interference peak is significantly suppressed. This indicates that the target channel is effectively enhanced through multi-comb despreading merging, while the interference signal is effectively suppressed due to the low cross-correlation characteristics of the coding. The figure above visually demonstrates the ability of the method of this invention to suppress interference and enhance the target signal in multi-channel signal processing.

[0102] Figure 6 This demonstrates the effect of the number of activated comb teeth in the method of the present invention. L The changes in processing gain and crosstalk suppression effect are increased. In the figure, the horizontal axis represents the number of activated comb teeth. L The vertical axis represents processing gain (SNR, the ratio of target signal to noise signal) and signal-to-interference ratio (SIR, the ratio of target signal to interference signal), respectively. Through different... L The experimental results clearly show that as the number of comb teeth increases, both the system's processing gain and signal-to-interference ratio exhibit a significant upward trend. Specifically, the processing gain increases with... L The increase in gain approaches the theoretical gain, while the improvement in signal-to-interference ratio indicates that the method of the present invention suppresses interference from non-target channels through coherent merging across the comb teeth, further improving the detectability of the target signal. Figure 6 This invention verifies that, under multi-comb activation conditions, it achieves higher target detection performance and stronger interference suppression capability.

[0103] Embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0104] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0105] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0106] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0107] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A comb-domain encoded frequency-modulated continuous wave lidar device, characterized in that, include: The system comprises an optical frequency comb, an optical beam splitter, a measurement branch, a local oscillator branch, a transmitting optical system, an optical beam combiner, a dense wavelength division multiplexer, a photodetector array, and a data processing system. The optical frequency comb is connected to the optical beam splitter. The optical beam splitter is connected to the measurement branch and the local oscillator branch. The local oscillator branch is connected to the transmitting optical system via an optical circulator. The transmitting optical system and the local oscillator branch are connected to the dense wavelength division multiplexer via the optical beam combiner. The dense wavelength division multiplexer is connected to the photodetector array. The photodetector array is connected to the data processing system. The measurement branch includes a programmable optical filter, a first polarization controller, and a first I / Q optical modulator. The optical beam splitter is connected to the programmable optical filter, the programmable optical filter is connected to the first polarization controller, the first polarization controller is connected to the first I / Q optical modulator, the first I / Q optical modulator is connected to the optical circulator, and the first I / Q optical modulator outputs a frequency-modulated continuous wave measurement optical comb signal. The optical comb is encoded using a programmable optical filter to generate a subset of active comb teeth and a complex weighted code for each active comb tooth. The local oscillator branch includes a second polarization controller and a second I / Q optical modulator. The optical beam splitter is connected to the second polarization controller, the second polarization controller is connected to the second I / Q optical modulator, the second I / Q optical modulator is connected to the optical beam combiner, and the second I / Q optical modulator outputs a frequency-modulated continuous local oscillator optical comb signal. The transmitting optical system includes a collimator and a transmission grating. The optical circulator connects the collimator and the optical beam combiner. The collimator is connected to the transmission grating. The frequency-modulated continuous wave measurement optical comb signal is transmitted to the space scene to be measured through the optical circulator, collimator and transmission grating, and the echo is received. The echo is output to the optical beam combiner through the optical circulator. The device also includes an arbitrary waveform generator, a first electrical beam splitter, a second electrical beam splitter, a bias controller, and a third point beam splitter. The arbitrary waveform generator is connected to the first I / Q optical modulator and the second I / Q optical modulator respectively through the first and second electrical beam splitters for driving and controlling them. The bias controller is connected to the first I / Q optical modulator and the second I / Q optical modulator through the third electrical beam splitter for providing DC bias and setting the operating point.

2. The comb-domain encoded frequency-modulated continuous wave lidar device according to claim 1, characterized in that, The first electrical beam splitter is connected to the RF1 terminal of the first I / Q optical modulator and the second I / Q optical modulator, the second electrical beam splitter is connected to the RF2 terminal of the first I / Q optical modulator and the second I / Q optical modulator, and the third electrical beam splitter is connected to the DC terminal of the first I / Q optical modulator and the second I / Q optical modulator.

3. The comb-domain encoded frequency-modulated continuous wave lidar device according to claim 1, characterized in that, The optical frequency comb is a mode-locked laser, a microcavity optical comb, or an electro-optic modulation optical comb.

4. The comb-domain encoded frequency-modulated continuous wave lidar device according to claim 1, characterized in that, The optical circulator is provided with a first port, a second port and a third port. The first port of the optical circulator is connected to the first I / Q optical modulator, the second port is connected to the collimator and the third port is connected to the optical beam combiner.

5. A measurement method for a comb-domain encoded frequency-modulated continuous wave lidar device, applied to the comb-domain encoded frequency-modulated continuous wave lidar device according to any one of claims 1-4, characterized in that, include: Step 1: Construct a comb-domain encoded frequency-modulated continuous wave lidar device, activate the optical frequency comb, and generate a frequency-modulated continuous wave lidar device containing... K The optical frequency of the comb teeth; Step 2: Use an arbitrary waveform generator to set the modulation parameters of the linear frequency modulation signal, and configure the frame sequence in the arbitrary waveform generator so that different frames output different sweep directions of drive; Step 3: Encode the optical comb domain using a programmable optical filter to generate an active comb tooth subset and generate a complex weighted code for each active comb tooth; Step 4: Input the encoded optical comb into the first I / Q optical modulator and generate the measurement optical comb by continuous linear frequency modulation in a single-sideband manner, and emit it through the transmitting optical system; at the same time, the second I / Q optical modulator generates a local oscillator optical comb with the same slope as the measurement optical comb; Step 5: Receive the echo, combine it with the local oscillator optical comb, and input it into a dense wavelength division multiplexer for wavelength division. Perform mixing and photoelectric detection on each comb branch to obtain the beat frequency electrical signal of the corresponding comb. Step 6: Sample the beat frequency electrical signal and perform a fast Fourier transform within each frame to obtain discrete beat frequency observations; Step 7: Perform matched filtering, despreading, and merging on the discrete beat frequency observations based on comb domain coding to obtain the beat spectrum of the target channel after removing interference; Step 8: Based on the beat spectrum after removing interference from the target channel, perform peak detection on the beat spectrum in adjacent upper and lower sweep frequencies, extract the upper and lower sweep frequency beat frequencies corresponding to the same target, and solve for the distance and velocity of the target.

6. The measurement method of a comb-domain encoded frequency-modulated continuous wave lidar device according to claim 5, characterized in that, In step 1, the first is defined. The optical frequency of the comb teeth is: ； In the formula, The starting frequency; The spacing between the comb teeth; K This refers to the number of comb teeth.

7. The measurement method of a comb-domain encoded frequency-modulated continuous wave lidar device according to claim 6, characterized in that, In step 3, the optical comb is encoded using a programmable optical filter to generate an active comb tooth subset, specifically as follows: In containing K In the optical frequency comb signal of a comb tooth, a portion of the comb teeth are selected to participate in transmission and modulation, while the remaining comb teeth are turned off or strongly attenuated in the frame. Each comb tooth corresponds to a transmitter or channel. The transmitter, in the... The frame determines the activation subset as follows: ； Generate comb domain encoding complex weights for each activated comb tooth, as follows: ； In the formula, This is the amplitude code, used for amplitude weighting or on / off key control. =0 indicates that the comb tooth is not active in this frame; This is a phase code used for the design of separability between different channels; For the first The transmitter was in the... Frame applied to the first The coding of the comb teeth; For different transmitters or channels When generating comb field encoding, make any The low cross-correlation constraint is satisfied on its active comb intersection as follows: ； In the formula, For the first The transmitter was in the... Frame applied to the first The coding of the comb teeth, ( ) * Indicates conjugate. It is limited to not exceeding a preset threshold; For the first The transmitter was in the... The activation subset of the frame; The optical comb is input into a programmable optical filter, and complex amplitude equalization is applied to each comb tooth. A k Comb field encoding The inactive comb teeth are then subjected to strong attenuation to obtain the encoded optical comb output.

8. The measurement method of a comb-domain encoded frequency-modulated continuous wave lidar device according to claim 7, characterized in that, In step 8, based on the beat spectrum after interference removal from the target channel, peak detection is performed on the beat spectrum in adjacent upper and lower sweep frequencies. The upper and lower sweep beat frequencies corresponding to the same target are extracted to solve for the distance and velocity of the target. Specifically: Based on the beat spectrum after interference removal from the target channel, peak detection is performed on the beat spectrum in adjacent up-sweep and down-sweep frequencies to extract the up-sweep beat frequency corresponding to the same target. With downscan frequency and beat frequency The solution is obtained for the target being measured. The distance and speed are: ； In the formula, The distance to the target object in the target channel. The measured velocity of the target channel. At the speed of light, This is the operating wavelength.

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